UPDATED: An explosion in the Chelsea neighborhood of New York City has injured at least 29 people, according to the New York Fire Department.

The blast happened around Saturday night at 8:30pm local time at the intersection of West 23rd Street and 6th Avenue. The NYPD Counterterrorism Unit says one of the 29 injuries “may be critical.” Some of the injured were transferred to Bellevue Hospital.

A law enforcement source told CNN that the preliminary cause of the explosion is an IED (improvised explosive device) in or near a trash dumpster, but the cause is still under investigation. Gas has been ruled out as a cause.

“Tonight New York City experienced a very serious incident,” Mayor Bill de Blasio said at a press conference later on Saturday. “There is no evidence of a terror connection to the incident.”

“There is no significant or credible threat to New York City from any terror organization,” he added. “Early indications are this was an intentional act.”

“As of this time, the exact cause of the explosion has not been determined,” Police commissioner James O’Neill said Saturday night. “There have been 29 injuries reported. One of these injuries can be considered serious.”

The area has been closed off while law enforcement sweeps for any additional devices and removes debris. The local subway station has been closed as well. According to eyewitnesses, many car and building windows have been blown out. Bomb sniffing dogs are searching the neighborhood and beyond for additional devices.

The NYC explosion follows another that happened in Seaside Park, New Jersey. A pipe bomb exploded in a trash can near a Marine Corp race. No one was injured. The FBI is investigating the New Jersey explosion. There does not appear to be a connection between the two explosions at this time.

President Obama has been briefed on the explosion.